This invention is generally directed to processes for the preparation of photogenerating components, and more specifically the present invention is directed to processes for obtaining photogenerating pigments such as perylenes, perinones, and phthalocyanines, especially titanyl phthalocyanine, reference for example U.S. Pat. No. 4,898,799, the disclosure of which is totally incorporated herein by reference. In one embodiment, the present invention is directed to a process for the preparation of perylenes, perinones, and phthalocyanines, such as metal free phthalocyanines, metal phthalocyanines, vanadyl phthalocyanines, titanyl phthalocyanines and the like by initially providing, for example, the phthalocyanine, such as titanyl phthalocyanine, or accomplishing the preparation thereof by, for example, the reaction of titanium tetra(propoxide) with a mixture of phthalonitrile and diaminoisoindolene in a 1-methylpyrrolidinone solvent; dissolving the resulting polymorph in a solvent mixture of trifluoroacetic acid and toluene; and thereafter precipitating the desired photogenerating pigment by, for example, adding with stirring the aformentioned mixture to water, separating the product therefrom by, for example, filtration, and washing the product obtained. The photogenerating pigments obtained, which in one embodiment of the present invention are of small particle size diameter, such as, for example, from about 0.05 micron to about 1 micron, including titanyl phthalocyanines, especially the polymorph II, can be selected as organic photogenerator pigments in photoresponsive imaging members containing charge transport layers such as aryl amine hole transport molecules. The aforementioned photoresponsive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the substrate; or positively charged when the hole transport layer is situated between the photogenerating layer and the supporting substrate. The layered photoconductor imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic processes wherein negatively charged or positively charged images are rendered visible with toner compositions of the appropriate charge. Generally, the imaging members are sensitive in the wavelength regions of from about 400 to about 800 nanometers, depending on the photogenerator selected, thus diode lasers can be selected as the light source for imaging members sensitive to wavelengths of from about 700 to about 800 nanometers.
Processes for the preparation of phthalocyanines, such as titanyl phthalocyanine, are known, however, many of them require the use of a strong acid such as sulfuric acid, and these processes are not easily scalable. One process as illustrated in Konica Japanese Laid Open on Jan. 20, 1989 as 64-17066, the disclosure of which is totally incorporated herein by reference, involves the reaction of titanium tetrachloride and phthalodinitrile in an alpha-chloronaphthalene solvent to produce dichlorotitanium phthalocyanine which is then subjected to hydroylsis by ammonia water to enable alpha-type phthalocyanine. This phthalocyanine is preferably treated with an electron releasing solvent such as 2-ethoxyethanol, dioxane, 1-methylpyrrolidinone, followed by subjecting the alpha-titanyl phthalocyanine to milling at a temperature of from 50.degree. to 180.degree. C. In a second method described in the aforementioned Japanese Publication, there is disclosed the preparation of alpha-type titanyl phthalocyanine with sulfuric acid. Another method for the preparatrion of alpha-titanyl phthalocyanine involves the addition of an aromatic hydrocarbon, such as dichlorobenzene, solvent to an aqueous suspension of the phthalocyanine, and heating, reference Japanese Laid Open 20365/1988, laid open Jan. 28, 1988 . In Japanese 171771/1986, laid open Aug. 2, 1986, there is disclosed the purification of metalloxy phthalocyanine by treatment with 1-methylpyrrolidinone. Imaging members with the above prepared prior art phthalocyanines are also known.
Generally, layered photoresponsive imaging members are described in a number of U.S. patents, such as U.S. Pat. No. 4,265,900, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. Examples of photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanines, and metal free phthalocyanines. Additionally, there is described in U.S. Pat. No. 3,121,006 a composite xerographic photoconductive member comprised of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in the '006 patent comprise a material which is incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles.
Photoresponsive imaging members with squaraine photogenerating pigments are also known, reference U.S. Pat. No. 4,415,639. In this patent there is illustrated a photoresponsive imaging member with a substrate, a hole blocking layer, an optional adhesive interface layer, an organic photogenerating layer, a photoconductive composition capable of enhancing or reducing the intrinsic properties of the photogenerating layer, and a hole transport layer. As photoconductive compositions for the aforementioned member there can be selected various squaraine pigments, including hydroxy squaraine compositions. Moreover, there is disclosed in U.S. Pat. No. 3,824,099 certain photosensitive hydroxy squaraine compositions.
The use of selected perylene pigments as photoconductive substances is also known. There is thus described in Hoechst European Patent Publication 0040402, DE3019326, filed May 21, 1980, the use of N,N'-disubstituted perylene-3,4,9,10-tetracarboxyldiimide pigments as photoconductive substances. Specifically, there is disclosed in this publication evaporated N,N'-bis(3-methoxypropyl)-perylene-3,4,9,10-tetracarboxyldiimid e dual layered negatively charged photoreceptors with improved spectral response in the wavelength region of 400 to 700 nanometers. A similar disclosure is revealed in Ernst Gunther Schlosser, Journal of Applied Photographic Engineering, Vol. 4, No. 3, page 118 (1978). There is also disclosed in U.S. Pat. No. 3,871,882 photoconductive substances comprised of specific perylene-3,4,9,10-tetracarboxylic acid derivative dyestuffs. In accordance with the teachings of this patent, the photoconductive layer is preferably formed by vapor depositing the dyestuff in a vacuum. Also, there is specifically disclosed in this patent dual layer photoreceptors with perylene-3,4,9,10-tetracarboxylic acid diimide derivatives, which have spectral response in the wavelength region of from 400 to 600 nanometers. Also, in U.S. Pat. No. 4,555,463, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a chloroindinium phthalocyanine photogenerating layer. In U.S. Pat. No. 4,587,189, the disclosure of which is totally incorporated herein by reference there is illustrated a layered imaging member with a perylene pigment photgenerating component. Both of the aformentioned patents disclose an aryl amine component as a hole transport layer.
Moreover, there is disclosed in U.S. Pat. No. 4,419,427 electrographic recording media with a photosemiconductive double layer comprised of a first layer containing charge carrier perylene diimide producing dyes, and a second layer with one or more compounds which are charge transporting materials when exposed to light, reference the disclosure in column 2, beginning at line 20. Also of interest with respect to this patent is the background information included in columns 1 and 2, wherein perylene dyes of the formula illustrated are presented.
There is illustrated in U.S. Pat. No. 4,574,482, entitled Photoconductive Devices Containing Perylene Dye Compositions, the disclosure of which is totally incorporated herein by reference, an ambipolar imaging member comprised of a supporting substrate, a photoconductive layer comprised of specific perylene dyes different than the perylene pigments of the present invention, which dyes are dispersed in a polymeric resinous binder composition, and as a top layer a specific aryl amine hole transporting substance dispersed in an inactive resinous binder.
In copending application U.S. Ser. No. 537,714 (D/90087), the disclosure of which is totally incorporated herein by reference, there are illustrated photoresponsive imaging members with photogenerating titanyl phthalocyanine layers prepared by vacuum deposition. It is indicated in this copending application that the imaging members comprised of the vacuum deposited titanyl phthalocyanines and aryl amine hole transporting compounds exhibit superior xerographic performance as low dark decay characteristics result and higher photosensitivity is generated, particularly in comparison to several prior art imaging members prepared by solution coating or spray coating, reference for example U.S. Pat. No. 4,429,029 mentioned hereinbefore.
In copending application U.S. Ser. No. 533,261 (D/90198), the disclosure of which is totally incorporated herein by reference, there is disclosed, for example, a process for the preparation of titanyl phthalocyanine which comprises dissolving a titanyl phthalocyanine in a solution of trifluoroacetic acid and methylene chloride; adding the resultant solution to a solvent system that will enable precipitation; and separating the desired titanyl phthalocyanine from the solution followed by an optional washing.
In copending application U.S. Ser. No. 533,265 (D/90244), the disclosure of which is totally incorporated herein by reference, there is disclosed, for example, a process for the preparation of phthalocyanine composites which comprises adding a metal free phthalocyanine, a metal phthalocyanine, a metalloxy phthalocyanine or mixtures thereof to a solution of trifluoroacetic acid and a monohaloalkane; adding to the resulting mixture a titanyl phthalocyanine; adding the resulting solution to a mixture that will enable precipitation of said composite; and recovering the phthalocyanine composite precipitated product.